This invention relates generally to a device which provides assistance in breathing during cold weather and more particularly to a breathing mask which heats and humidifies incoming air.
Cold weather breathing aids of various types have been proposed in the past, as exemplified by my earlier patents, U.S. Pat. Nos. 4,269,183 and 4,473,071, my pending patent application, Ser. No. 588,088, filed Mar. 9, 1984, and U.S. Pat. Nos. 4,150,671 and 4,412,537 to Tiger. Although the devices disclosed in these patents are generally helpful in that they preheat air which is to be inhaled in cold weather, all of the them are subject to problems. Some of the devices present "dead space" in which carbon dioxide can collect and possibly degrade the quality of the incoming air. Prior devices are also plagued by aesthetic problems and by bulkiness which makes them uncomfortable to wear and hard to handle and store. They are also difficult to put on and take off and are not always securely held in place on the face.
Prior devices have been somewhat ineffective in preheating the incoming air and do not humidify the air at all or at best only minimally. Devices that rely on heat transfer to intake tubes or air bladders do not always heat the incoming air effectively because the heat must be transferred from the exhaled air through the tube or bladder walls and then to the incoming air. It is also necessary to first heat the parts of the device which are used to transfer heat to incoming air. If the device itself is cold (due to having been left outside or in a cold car or garage, for example), it takes sometime to heat up the parts before they can effectively heat the incoming air. Body heat is not used to full advantage in prior devices and, if used at all, serves only to indirectly heat the air. Restriction of the airflow through tubing or reservoir bladders has also been a problem with prior devices.
The present invention is directed to a cold weather breathing mask which heats and humidifies incoming air more effectively than prior masks. In accordance with the invention, a mask which fits over the mouth and nose is equipped with a U-shaped foam conduit which extends along opposite sides of the face, head and neck. A corrugated metal partition divides the conduit into side by side intake and exhaust passages which communicate with the interior of the mask through one way valves. Air is drawn into the intake passages and flows through them in direct contact with the head, neck and face to effectively extract heat and moisture from the skin prior to entering the mask. The warm exhaled air flows through the exhaust passages and transfers heat through the metal partition to the incoming air which flows in a direction counter to the exhaled air.
The incoming air is thus preheated directly by body heat radiated from the face, head and neck and indirectly by the heat contained in the exhaled air. Normally, heat from the head area is sufficient by itself to heat the air to the desired temperature, although in particularly cold weather, the heat from the exhaled air can also be used to achieve more rapid heating. The open sides of the intake passages are sealed against the head and securely held in place so that the face, head and neck actually form one side of each intake passage. Therefore, the incoming air directly contacts the face, head and neck area and is directly heated and humidified. At the same time, the corrugated metal partition provides an excellent heat conductor which effectively transfers heat from the warm exhaled air to the cold incoming air. The corrugations increase the effective surface area of the partition and thus enhance its heat transfer properties.
The construction of the device is devoid of tubing, and thus there is no inspiratory or expiratory resistance to air flow that is associated with the prior art devices. The device is also less bulky to wear and less cumbersome to handle than masks which include lengths of tubing. The device is easy to put on and take off, and it is not subject to the aesthetic problems that result from the presence of tubing or unsightly straps. There is no need for a muffler, a hat or any other accessory to be worn, although they can be worn without interfering with the breathing mask.